Which processor configuration is used by the Dell EMC PowerEdge R740 server?

A Dell EMC PowerEdge 14G server uses Intel OPTANE DC Persistent Memory in App Direct mode. What is the minimum size DIMM supported for this type of memory?

You are Investigating a disk error on a Dell EMC PowerEdge server and discover a Hot Spare has not been assigned to the Virtual Disk Group. Use the simulator to assign the Global Hot Spare. When you have finished using the simulator, dick Next.

How can a technician know whether IDRAC9 System Lockdown mode is enabled?

An engineer needs to install an additional PSU on an existing, single PSU Dell EMC PowerEdge R740. They complete the initial installation and cabling procedures. They connect an AC cable and the power distribution unit produces normal AC output. The engineer checks power management and sees that the new PSU is in the Failed state.
What task should be completed to troubleshoot this issue?